Lower drivers seat position
Discussion
To gain some extra headroom in the cabin, I’d like to explore taking my original seats off the rails and bolt to the floor. Has anyone done this and can give me some pointers - especially where I’d attach bolts / attachments to on the underside of the seat. Other threads only seem to discuss doing this with alternative seats.
I’m pretty tall at 6’7” and a snug fit in my ‘98 Chim. So far, I’ve optimised my seating position by adjusting seat rake and position, and moved pedals fully forward. But I still occasionally catch my head on the roof hoop on larger bumps and my knees are restricted by the bottom of the dash.
I can see there are those riser blocks on the front of the seat, but taking those out alone won’t really help as it’s the rear of the seat that has to drop.
.. and no, roof off only helps if I have the rear section folded back as well and it’s not p*****g down!
I’m pretty tall at 6’7” and a snug fit in my ‘98 Chim. So far, I’ve optimised my seating position by adjusting seat rake and position, and moved pedals fully forward. But I still occasionally catch my head on the roof hoop on larger bumps and my knees are restricted by the bottom of the dash.
I can see there are those riser blocks on the front of the seat, but taking those out alone won’t really help as it’s the rear of the seat that has to drop.
.. and no, roof off only helps if I have the rear section folded back as well and it’s not p*****g down!
If you remove one of the seats which is done by removing the 4 nuts holding them through the floor you can then measure the bolt positions that hold the seat to the rails.
That will be the deciding factor because they may not sit flush or flat to the floor which could make the fixing unsafe.
The floor is about 2.5 mm thick and not very strong so I’d use spreader washers on both inside and outside the car to make the floor stronger around any new holes you drill.
I’d be inclined to add a few layers of fibreglass to the floor inside the car where your new holes would be drilled and that should make your fixing points stronger than original.
What you might find is water enters the car and seats on the floor could induce a wet ass through capillary action.
That will be the deciding factor because they may not sit flush or flat to the floor which could make the fixing unsafe.
The floor is about 2.5 mm thick and not very strong so I’d use spreader washers on both inside and outside the car to make the floor stronger around any new holes you drill.
I’d be inclined to add a few layers of fibreglass to the floor inside the car where your new holes would be drilled and that should make your fixing points stronger than original.
What you might find is water enters the car and seats on the floor could induce a wet ass through capillary action.
You can also create a support underneath like VT automotive is (was?) doing.
But I always wonder why this was not done like this from the factory, could it be that fixing the seats to the chassis is more dangerous than to the fiber? This sounds weird unless there is something linked to the absorption of the shock?
But I always wonder why this was not done like this from the factory, could it be that fixing the seats to the chassis is more dangerous than to the fiber? This sounds weird unless there is something linked to the absorption of the shock?
Why didn't TVR do that? Because drilling eight holes through GRP takes 5-minutes 
Nice solution but lowers the ground clearance in the middle of the car. Weld in some straps come chassis refurb time.
As for the OP's seat question.
What condition are the seats in? You could get the bases re-foamed with a thinner build up in firmer foam. And the metal wire support grid replaced with fabric webbing. This would gain you more height than removing the runners and still retain the sliders - not an issue for you but come sale time ..
Alternatively, and this is an expensive option, source some Cerbera seats - not the Tuscan 'hoop' ones - and fit a thinned foam base and webbing during a re-trim. Fit some heated seat elements too. In my opinion, the best around seats TVR every fitted. Comfortable, supportive and look good.
Nice solution but lowers the ground clearance in the middle of the car. Weld in some straps come chassis refurb time.
As for the OP's seat question.
What condition are the seats in? You could get the bases re-foamed with a thinner build up in firmer foam. And the metal wire support grid replaced with fabric webbing. This would gain you more height than removing the runners and still retain the sliders - not an issue for you but come sale time ..
Alternatively, and this is an expensive option, source some Cerbera seats - not the Tuscan 'hoop' ones - and fit a thinned foam base and webbing during a re-trim. Fit some heated seat elements too. In my opinion, the best around seats TVR every fitted. Comfortable, supportive and look good.
Thanks, all useful input in their own way!
Progress update. I’ve had the seat out and looked things over and measured up.
I was able to lose 5mm at the rear of the seat straight away just by changing the fixing bolt arrangement.
I can gain a further 10mm by removing the runners and bolting to the floor.
- I can reuse the fixing holes in the seat base where the runners attach, to bolt to the floor
- I may need to drill 4 new holes in the floor to position the seat where it’ll need to be.
- I can’t see that this would necessarily be less structurally sound than with rails. It’s still only a 4-point attachment. It would be simple enough to add further strengthening with fibre glass or spreader plates of some sort.
The car underwent a full body of resto just 2-years ago with the previous owner. Including re-trim, so the seat base is still quite plump - I’ll now explore a way of either thinning that out or loosening the support. That said, I’m 100kg, so in time it’ll droop!
Oh, and whoever fitted the seats last didn’t apply any sealant around the holes.
Right then, off to test the extra 5mm before it p****s down with rain again!
Progress update. I’ve had the seat out and looked things over and measured up.
I was able to lose 5mm at the rear of the seat straight away just by changing the fixing bolt arrangement.
I can gain a further 10mm by removing the runners and bolting to the floor.
- I can reuse the fixing holes in the seat base where the runners attach, to bolt to the floor
- I may need to drill 4 new holes in the floor to position the seat where it’ll need to be.
- I can’t see that this would necessarily be less structurally sound than with rails. It’s still only a 4-point attachment. It would be simple enough to add further strengthening with fibre glass or spreader plates of some sort.
The car underwent a full body of resto just 2-years ago with the previous owner. Including re-trim, so the seat base is still quite plump - I’ll now explore a way of either thinning that out or loosening the support. That said, I’m 100kg, so in time it’ll droop!
Oh, and whoever fitted the seats last didn’t apply any sealant around the holes.
Right then, off to test the extra 5mm before it p****s down with rain again!
I had a look at the floor with the carpet up. There’s a ‘box ridge’ that runs front to back on each side of the floor pan, which the seat rails run along - albeit they’re raised off the floor. This ridge looks to provide additional structural integrity for the seat fittings. So drilling / bolting anywhere along that ought to be ok.
Classic Chim said:
If you remove one of the seats which is done by removing the 4 nuts holding them through the floor you can then measure the bolt positions that hold the seat to the rails.
That will be the deciding factor because they may not sit flush or flat to the floor which could make the fixing unsafe.
The floor is about 2.5 mm thick and not very strong so I’d use spreader washers on both inside and outside the car to make the floor stronger around any new holes you drill.
I’d be inclined to add a few layers of fibreglass to the floor inside the car where your new holes would be drilled and that should make your fixing points stronger than original.
What you might find is water enters the car and seats on the floor could induce a wet ass through capillary action.
That will be the deciding factor because they may not sit flush or flat to the floor which could make the fixing unsafe.
The floor is about 2.5 mm thick and not very strong so I’d use spreader washers on both inside and outside the car to make the floor stronger around any new holes you drill.
I’d be inclined to add a few layers of fibreglass to the floor inside the car where your new holes would be drilled and that should make your fixing points stronger than original.
What you might find is water enters the car and seats on the floor could induce a wet ass through capillary action.
The Cerbera seats option sounds good, but I’d want to try them out in some else’s car before splashing out on them.
mk1fan said:
Why didn't TVR do that? Because drilling eight holes through GRP takes 5-minutes
Nice solution but lowers the ground clearance in the middle of the car. Weld in some straps come chassis refurb time.
As for the OP's seat question.
What condition are the seats in? You could get the bases re-foamed with a thinner build up in firmer foam. And the metal wire support grid replaced with fabric webbing. This would gain you more height than removing the runners and still retain the sliders - not an issue for you but come sale time ..
Alternatively, and this is an expensive option, source some Cerbera seats - not the Tuscan 'hoop' ones - and fit a thinned foam base and webbing during a re-trim. Fit some heated seat elements too. In my opinion, the best around seats TVR every fitted. Comfortable, supportive and look good.
Nice solution but lowers the ground clearance in the middle of the car. Weld in some straps come chassis refurb time.
As for the OP's seat question.
What condition are the seats in? You could get the bases re-foamed with a thinner build up in firmer foam. And the metal wire support grid replaced with fabric webbing. This would gain you more height than removing the runners and still retain the sliders - not an issue for you but come sale time ..
Alternatively, and this is an expensive option, source some Cerbera seats - not the Tuscan 'hoop' ones - and fit a thinned foam base and webbing during a re-trim. Fit some heated seat elements too. In my opinion, the best around seats TVR every fitted. Comfortable, supportive and look good.
My previous car was like that, and had far fewer dents in my head from it 
s p a c e m a n said:
I'm 6'3 and fitted in perfectly with loads of room when the metal wire on the bottom of the seat rusted away and I was basically sitting on a foam pad on the floor. It means that you can only slide the seat around when you're not sitting in it, but I didn't bang my head once 
A quick update on the solution I’ve gone with for now.
I took the seat out again with the intention of removing the rails and bolting it to the floor. But when I looked at the underneath of the seat base I noticed the foam padding was stained blue approx where my bum sits. It was clear then that the base of the seat was touching the carpet, so actually lowering the seat itself wasn’t going to gain me any extra headroom.
As the base of the seat is formed with 45mm thick dense foam I decided to replace the section where your bum sits with some thinner memory foam. I left the front section which supports your thighs as-is. I also replaced the base support wires with elasticated webbing.
In essence this created more of bucket seat effect and gained me the extra headroom I was after. It’s turned out to be pretty comfortable as well!
I took the seat out again with the intention of removing the rails and bolting it to the floor. But when I looked at the underneath of the seat base I noticed the foam padding was stained blue approx where my bum sits. It was clear then that the base of the seat was touching the carpet, so actually lowering the seat itself wasn’t going to gain me any extra headroom.
As the base of the seat is formed with 45mm thick dense foam I decided to replace the section where your bum sits with some thinner memory foam. I left the front section which supports your thighs as-is. I also replaced the base support wires with elasticated webbing.
In essence this created more of bucket seat effect and gained me the extra headroom I was after. It’s turned out to be pretty comfortable as well!
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